Here are the relative shares, as Liz calculates them. (The
shares will look unfamiliar, because Liz is assessing each
company's share of the whole US search query market, instead of
the relative share of the top 5.)

In a few months, Facebook will have left Ask and AOL in
the dust. Facebook will also likely be catching up
with Bing, without having to shell out massive dollars for
toolbar distribution, the way Microsoft is doing.

Taken together, all the non-Google players still have
only 27% of the market. Google has 60%. The
other 13% is presumably distributed in tiny shares. This
"other" will gradually disappear, as Bing or another provider
becomes the back-end engine for everyone but Google. The
possible exception is if Apple makes a big push here.

If Bing buys the Facebook search business (pays Facebook
a huge share of each query to serve the results) and Facebook's
share continues to grow, then it's possible Bing could cobble
together 35%-40% of the search market just by buying
it. Importantly,
Microsoft's economics on this 35%-40% will be horrible relative
to Google's, because it will have to pay majority revenue
share for most ot it. But there does seem to be a path for
Microsoft to control those queries. IF Facebook agrees to a
deal.